This invention pertains to bicycle construction, and more particularly, to a mechanism in the frame of a bicycle for clamping onto and thereby mounting the pillar of a bicycle seat.
A typical means for mounting the pillar of a bicycle seat in a bicycle frame includes a split or slotted collar or lug which fits around the upper end of the usual seat tube in the frame, with this tube also including a slot which is generally aligned with that provided in the collar. Opposed, outwardly bent projecting ears are provided on the collar on opposite sides of the slot therein, through which a nut and bolt assembly, or the like, may be inserted and actuated for drawing the collar, and hence, the upper end of the seat tube, tightly against such a pillar.
Several problems exist with this construction. To begin with, slotting of the seat tube weakens it. Secondly, where the ears bend there exist regions of high stress with usually little supporting mass to prevent fatiguing with repeated mountings and demountings of a seat.
A general object of the present invention is to provide an improved form of clamping mechanism which simplifies a mounting and demounting operation for a seat, affords more reliable clamping, and which also promotes a superior overall construction for a bicycle frame.
Still another object of the invention is to provide such a mechanism wherein, unlike the outwardly projecting lugs in a conventional clamping mechanism, clamping members are concealed within the inside of the frame, thus to enhance significantly the appearance of the frame in the region where the seat is mounted.
According to a preferred embodiment of the invention, the proposed clamping mechanism includes a pair of spaced relatively movable clamping parts which are disposed within the rear end of the usual top frame tube in a bicycle frame, with these two members having concave, cylindrical clamping surfaces which face, through an opening, into the interior of the upper end of the usual seat tube in the frame. One of the clamping members is preferably secured to the top tube, and the other is movable therewithin. A bolt, such as an Allenhead-type bolt, extends between the clamping members, with the head of this bolt suitably recessed within an outwardly facing socket provided in the fixed clamping member and exposed through a single, suitable side opening in the top tube. This bolt may be adjusted to draw the clamping members relatively toward each other, or to shift them away from each other, to clamp onto and release the pillar of a seat inserted in the upper end of the seat tube.
The proposed clamping mechanism is therefore an extremely simple construction which functions highly effectively to clamp into the seat pillar. Further, the proposed mechanism promotes a superior overall frame construction inasmuch as slotting and weakening of the upper end of the seat tube is not necessary. In addition, the proposed construction affords an extremely streamlined appearance to that region of a bicycle where the seat is mounted.
These and other objects and advantages which are attained by the invention will become more fully apparent as the description which follows is read in conjunction with the accompanying drawings.